| //! `AstIdMap` allows to create stable IDs for "large" syntax nodes like items |
| //! and macro calls. |
| //! |
| //! Specifically, it enumerates all items in a file and uses position of a an |
| //! item as an ID. That way, id's don't change unless the set of items itself |
| //! changes. |
| |
| // FIXME: Consider moving this into the span crate |
| |
| use std::{ |
| any::type_name, |
| fmt, |
| hash::{BuildHasher, BuildHasherDefault, Hash, Hasher}, |
| marker::PhantomData, |
| }; |
| |
| use la_arena::{Arena, Idx, RawIdx}; |
| use profile::Count; |
| use rustc_hash::FxHasher; |
| use syntax::{ast, AstNode, AstPtr, SyntaxNode, SyntaxNodePtr}; |
| |
| use crate::db::ExpandDatabase; |
| |
| pub use span::ErasedFileAstId; |
| |
| /// `AstId` points to an AST node in any file. |
| /// |
| /// It is stable across reparses, and can be used as salsa key/value. |
| pub type AstId<N> = crate::InFile<FileAstId<N>>; |
| |
| impl<N: AstIdNode> AstId<N> { |
| pub fn to_node(&self, db: &dyn ExpandDatabase) -> N { |
| self.to_ptr(db).to_node(&db.parse_or_expand(self.file_id)) |
| } |
| pub fn to_in_file_node(&self, db: &dyn ExpandDatabase) -> crate::InFile<N> { |
| crate::InFile::new(self.file_id, self.to_ptr(db).to_node(&db.parse_or_expand(self.file_id))) |
| } |
| pub fn to_ptr(&self, db: &dyn ExpandDatabase) -> AstPtr<N> { |
| db.ast_id_map(self.file_id).get(self.value) |
| } |
| } |
| |
| pub type ErasedAstId = crate::InFile<ErasedFileAstId>; |
| |
| impl ErasedAstId { |
| pub fn to_ptr(&self, db: &dyn ExpandDatabase) -> SyntaxNodePtr { |
| db.ast_id_map(self.file_id).get_erased(self.value) |
| } |
| } |
| |
| /// `AstId` points to an AST node in a specific file. |
| pub struct FileAstId<N: AstIdNode> { |
| raw: ErasedFileAstId, |
| covariant: PhantomData<fn() -> N>, |
| } |
| |
| impl<N: AstIdNode> Clone for FileAstId<N> { |
| fn clone(&self) -> FileAstId<N> { |
| *self |
| } |
| } |
| impl<N: AstIdNode> Copy for FileAstId<N> {} |
| |
| impl<N: AstIdNode> PartialEq for FileAstId<N> { |
| fn eq(&self, other: &Self) -> bool { |
| self.raw == other.raw |
| } |
| } |
| impl<N: AstIdNode> Eq for FileAstId<N> {} |
| impl<N: AstIdNode> Hash for FileAstId<N> { |
| fn hash<H: Hasher>(&self, hasher: &mut H) { |
| self.raw.hash(hasher); |
| } |
| } |
| |
| impl<N: AstIdNode> fmt::Debug for FileAstId<N> { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| write!(f, "FileAstId::<{}>({})", type_name::<N>(), self.raw.into_raw()) |
| } |
| } |
| |
| impl<N: AstIdNode> FileAstId<N> { |
| // Can't make this a From implementation because of coherence |
| pub fn upcast<M: AstIdNode>(self) -> FileAstId<M> |
| where |
| N: Into<M>, |
| { |
| FileAstId { raw: self.raw, covariant: PhantomData } |
| } |
| |
| pub fn erase(self) -> ErasedFileAstId { |
| self.raw |
| } |
| } |
| |
| pub trait AstIdNode: AstNode {} |
| macro_rules! register_ast_id_node { |
| (impl AstIdNode for $($ident:ident),+ ) => { |
| $( |
| impl AstIdNode for ast::$ident {} |
| )+ |
| fn should_alloc_id(kind: syntax::SyntaxKind) -> bool { |
| $( |
| ast::$ident::can_cast(kind) |
| )||+ |
| } |
| }; |
| } |
| register_ast_id_node! { |
| impl AstIdNode for |
| Item, |
| Adt, |
| Enum, |
| Struct, |
| Union, |
| Const, |
| ExternBlock, |
| ExternCrate, |
| Fn, |
| Impl, |
| Macro, |
| MacroDef, |
| MacroRules, |
| MacroCall, |
| Module, |
| Static, |
| Trait, |
| TraitAlias, |
| TypeAlias, |
| Use, |
| AssocItem, BlockExpr, Variant, RecordField, TupleField, ConstArg, Param, SelfParam |
| } |
| |
| /// Maps items' `SyntaxNode`s to `ErasedFileAstId`s and back. |
| #[derive(Default)] |
| pub struct AstIdMap { |
| /// Maps stable id to unstable ptr. |
| arena: Arena<SyntaxNodePtr>, |
| /// Reverse: map ptr to id. |
| map: hashbrown::HashMap<Idx<SyntaxNodePtr>, (), ()>, |
| _c: Count<Self>, |
| } |
| |
| impl fmt::Debug for AstIdMap { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| f.debug_struct("AstIdMap").field("arena", &self.arena).finish() |
| } |
| } |
| |
| impl PartialEq for AstIdMap { |
| fn eq(&self, other: &Self) -> bool { |
| self.arena == other.arena |
| } |
| } |
| impl Eq for AstIdMap {} |
| |
| impl AstIdMap { |
| pub(crate) fn ast_id_map( |
| db: &dyn ExpandDatabase, |
| file_id: span::HirFileId, |
| ) -> triomphe::Arc<AstIdMap> { |
| triomphe::Arc::new(AstIdMap::from_source(&db.parse_or_expand(file_id))) |
| } |
| |
| fn from_source(node: &SyntaxNode) -> AstIdMap { |
| assert!(node.parent().is_none()); |
| let mut res = AstIdMap::default(); |
| |
| // make sure to allocate the root node |
| if !should_alloc_id(node.kind()) { |
| res.alloc(node); |
| } |
| // By walking the tree in breadth-first order we make sure that parents |
| // get lower ids then children. That is, adding a new child does not |
| // change parent's id. This means that, say, adding a new function to a |
| // trait does not change ids of top-level items, which helps caching. |
| bdfs(node, |it| { |
| if should_alloc_id(it.kind()) { |
| res.alloc(&it); |
| TreeOrder::BreadthFirst |
| } else { |
| TreeOrder::DepthFirst |
| } |
| }); |
| res.map = hashbrown::HashMap::with_capacity_and_hasher(res.arena.len(), ()); |
| for (idx, ptr) in res.arena.iter() { |
| let hash = hash_ptr(ptr); |
| match res.map.raw_entry_mut().from_hash(hash, |idx2| *idx2 == idx) { |
| hashbrown::hash_map::RawEntryMut::Occupied(_) => unreachable!(), |
| hashbrown::hash_map::RawEntryMut::Vacant(entry) => { |
| entry.insert_with_hasher(hash, idx, (), |&idx| hash_ptr(&res.arena[idx])); |
| } |
| } |
| } |
| res.arena.shrink_to_fit(); |
| res |
| } |
| |
| /// The [`AstId`] of the root node |
| pub fn root(&self) -> SyntaxNodePtr { |
| self.arena[Idx::from_raw(RawIdx::from_u32(0))] |
| } |
| |
| pub fn ast_id<N: AstIdNode>(&self, item: &N) -> FileAstId<N> { |
| let raw = self.erased_ast_id(item.syntax()); |
| FileAstId { raw, covariant: PhantomData } |
| } |
| |
| pub fn ast_id_for_ptr<N: AstIdNode>(&self, ptr: AstPtr<N>) -> FileAstId<N> { |
| let ptr = ptr.syntax_node_ptr(); |
| let hash = hash_ptr(&ptr); |
| match self.map.raw_entry().from_hash(hash, |&idx| self.arena[idx] == ptr) { |
| Some((&raw, &())) => FileAstId { raw, covariant: PhantomData }, |
| None => panic!( |
| "Can't find {:?} in AstIdMap:\n{:?}", |
| ptr, |
| self.arena.iter().map(|(_id, i)| i).collect::<Vec<_>>(), |
| ), |
| } |
| } |
| |
| pub fn get<N: AstIdNode>(&self, id: FileAstId<N>) -> AstPtr<N> { |
| AstPtr::try_from_raw(self.arena[id.raw]).unwrap() |
| } |
| |
| pub fn get_erased(&self, id: ErasedFileAstId) -> SyntaxNodePtr { |
| self.arena[id] |
| } |
| |
| fn erased_ast_id(&self, item: &SyntaxNode) -> ErasedFileAstId { |
| let ptr = SyntaxNodePtr::new(item); |
| let hash = hash_ptr(&ptr); |
| match self.map.raw_entry().from_hash(hash, |&idx| self.arena[idx] == ptr) { |
| Some((&idx, &())) => idx, |
| None => panic!( |
| "Can't find {:?} in AstIdMap:\n{:?}", |
| item, |
| self.arena.iter().map(|(_id, i)| i).collect::<Vec<_>>(), |
| ), |
| } |
| } |
| |
| fn alloc(&mut self, item: &SyntaxNode) -> ErasedFileAstId { |
| self.arena.alloc(SyntaxNodePtr::new(item)) |
| } |
| } |
| |
| fn hash_ptr(ptr: &SyntaxNodePtr) -> u64 { |
| BuildHasherDefault::<FxHasher>::default().hash_one(ptr) |
| } |
| |
| #[derive(Copy, Clone, PartialEq, Eq)] |
| enum TreeOrder { |
| BreadthFirst, |
| DepthFirst, |
| } |
| |
| /// Walks the subtree in bdfs order, calling `f` for each node. What is bdfs |
| /// order? It is a mix of breadth-first and depth first orders. Nodes for which |
| /// `f` returns [`TreeOrder::BreadthFirst`] are visited breadth-first, all the other nodes are explored |
| /// [`TreeOrder::DepthFirst`]. |
| /// |
| /// In other words, the size of the bfs queue is bound by the number of "true" |
| /// nodes. |
| fn bdfs(node: &SyntaxNode, mut f: impl FnMut(SyntaxNode) -> TreeOrder) { |
| let mut curr_layer = vec![node.clone()]; |
| let mut next_layer = vec![]; |
| while !curr_layer.is_empty() { |
| curr_layer.drain(..).for_each(|node| { |
| let mut preorder = node.preorder(); |
| while let Some(event) = preorder.next() { |
| match event { |
| syntax::WalkEvent::Enter(node) => { |
| if f(node.clone()) == TreeOrder::BreadthFirst { |
| next_layer.extend(node.children()); |
| preorder.skip_subtree(); |
| } |
| } |
| syntax::WalkEvent::Leave(_) => {} |
| } |
| } |
| }); |
| std::mem::swap(&mut curr_layer, &mut next_layer); |
| } |
| } |
